“空号”造句

“ 传号 ” 或 “ 空号 ” 条件是由两条线之间的电压来表示的.
The " mark " or'space " condition is represented by the voltage between two wires.

打过, 但那个号码是空号.
Yes, but the number's no longer in service.

这个号码现在是空号.
The number's no longer in service.

• #空号